In a video by Our Mexico of the Future, child actors play police, criminals and other adult roles, with the goal of highlighting the challenges facing Mexico. Nuestro Mexico Del Futuro hide caption

itoggle caption Nuestro Mexico Del Futuro

A photo provided by the California Department of Corrections shows killer Charles Manson, 77, on April 4, 2012. AP hide caption

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The arrest of an Occupy DC protester earlier this month in Washington — one type of arrest that would show up in the researchers' numbers. Nicholas Kamm /AFP/Getty Images hide caption

itoggle caption Nicholas Kamm /AFP/Getty Images